Three years ago, I reviewed the Essential Sound Products MusicCord Pro ES power cord. Although upmarket power cords engender strong opinions about whether they make a difference in the sound of hi-fi gear, I gave the cord and accompanying power strip a great review. I did not hear magic in my system, but I heard and measured incremental improvements in low-level noise as a result of its effective RF shielding, especially on unbalanced cables, with incremental sonic improvement in low bass. And, as importantly, these upscale cables netted a physical robustness to handle all my numerous plug/unplug cycles with the review gear.

Despite controversy over claimed audible improvements with upscale power cords, I have used them for years. I find that a good, well-made accessory power cord is better than the cheap power cords that come with most products, and the “tighter clamping force” of the plugs make for a more efficient conductor path that does not arc and produce stray noises. I am convinced that a tight connection and quality wire in the proper gauge can also help maintain tight accurate bass with a consistent flow of energy to the amplifier’s power supply.

Good accessory power cables also have better wire, accurate gauging, and stronger outer coating and strain relief connections that do not break easily. As a reviewer, I plug in and unplug components constantly and have had, in the last five years, four stock cables break at the thin strain-relief zone.

The Essence Reference-II

With my positive ESP power cord experience with the MusicCord Pro in mind, I decided to take a listen to the company’s top-tier audiophile cord — the Essence Reference-II, reviewed here. These pricier, made-in-USA power cords are a very good upgrade AC conduits, with tough durable build and quality wire that assures consistent current and shielding against potential AC noise. They are not low cost like the factory supplied cords, or those you get at the hardware store, but they are not as expensive as I have seen. A two meter Essence Reference-II cord is $1,999; the Essence Reference-II Power Distributor is $2,999.

The Essence Reference-II and its impressive, passive eight unit Essence Reference-II power strip, are the design pinnacle of Michael Griffin, the owner and designer of the Essential Sound Products. According to Griffin, the Essence Reference-II Power Cord is a testament to the old adage that sometimes “less is more.”

Griffin said that the Essence Reference-II’s pure copper is also employed throughout the entire current-carrying path; no other materials or plating is used.

My overall sonic impression — with the Essence Reference-II cords in place with the Pass Labs XA30.5 Class A MOSFET amp, MartinLogan Montis speakers and the Oppo BDP-105 feeding the Benchmark DAC2 D DAC — was that the sound was vividly tight in the bass with all the detail those wonderful ML Montis can reproduce through the electrostatics. Not a hint of extraneous noise.

“Our termination and epoxy fill process has been optimized to these new components,” Griffin notes. “Epoxy fill serves several key performance objectives. First, the epoxy we use has similar dielectric properties to the PVC insulation on the current-carrying conductors. This continuity of dielectric environment improves performance, versus the conductors going in and out of different dielectric environments. Second, the epoxy fill hermetically seals the termination components to prevent performance degradation due to oxidation and corrosion.”

Griffin explained that the hardened epoxy also provides superior strain relief to the conductor terminations. With most cable assemblies, the connector termination points are typically the weakest or most fragile part of a cable assembly. “With our power cords, the termination points are arguably the strongest,” he added.

A fitting companion to the Essence Reference-II power cable, the Essence Reference-II Power Distributor matches the power cord in its robust, overbuilt construction and similar electrical circuit refinements. Griffin insists that the heavy duty build can ensure against degraded performance as a result of “structural and airborne vibrations”.

Multiple-outlet distribution

The Essence Reference-II Power Distributor combines an aluminum chassis with excellent RF shielding characteristics and high mechanical rigidity — with numerous vibration isolation and damping techniques, including coating the internal walls and encapsulating the wiring harness assembly in a silicone damping material.

The Power Distributor is extra heavy duty

The internal wiring is assembled from multi-conductor shielded cable that is new and unique to the Reference-II, according to Griffin The distributor is wired in a “star’ or “home run” pattern where each duplex outlet is connected directly to the power cable, providing isolation. The duplex outlets are custom manufactured by Leviton. They are “hospital grade” and “isolated ground” with “line” and “neutral” contacts made from electrical grade bronze, which is 98% copper versus brass that is about 2/3 copper. The bronze contacts are not plated as is the case with most other hospital grade receptacles. Additional isolation, new for the Reference-II, has been added between the outlets and chassis, and wiring assembly and chassis walls, further lowering the noise floor. Of course, the power strips power cord is upgraded to a hard-wired Reference-II. The Essence Reference-II products are available in USA termination, or for our friends across the ocean, in European spec plugs. Ditto for the Power Distributor.The audition As with the MusicCord Pro ES, I conducted listening and measurement tests with unbalanced line cable placed near stock power cords to ascertain its noise rejection and suppression. With the stock cords on the Oppo BDP-105 and the Bryston BHA-1 headphone amp routed next to the RCA cables (Kimber Cable) , buzz and noise sidebands could be measured at -60 dB when playing CD test discs with silence tracks. With the headphone amp cranked up. I could hear the noise as well.

When I inserted the Essence Reference-II cords into the chain, the low-level hash was gone, no noise on the meter and no audible noise. Now, of course, this noise would not be heard with a normal signal, but it is noise that robs resolution from your system, and it is a testament to the ESP Essence Reference-II’s effectiveness. If you paid $100,000 for a top-end audiophile system that runs unbalanced cables, you would be happy knowing that these AC cords curb the noise. Of course, you could run balanced lines, if your system allows it, to cut down on the noise, but some purists prefer the single-ended approach.

My overall sonic impression — with the Essence Reference-II cords in place with the Pass Labs XA30.5Class A MOSFET amp, MartinLogan Montis speakers and the Oppo BDP-105 feeding the Benchmark DAC2 D DAC — was that the sound was vividly tight in the bass with all the detail those wonderful ML Montis can reproduce through the electrostatics. Not a hint of extraneous noise.

No noise is good noise

Replacing the Essence Reference-II with the factory cords seemed to loosen the bass a bit. And from a durability standpoint, you can understand my preference for better cords. During the test, one of the stock cords had a loose ground lug that actually produced some arcing buzz — unless I held it in the amp’s receptacle very tightly.

The Power Distributor did not add any additional noise-suppression properties, but I felt better having this big gun in the system; the heavy, passive strip’s eight premium outlets came in handy for my review duties, and its size allowed all these heavy cables to be plugged in without pulling the strip over. This the best power strip I have ever used when it comes to handling a gaggle of heavy duty power cords. And it does not hurt, to have the same cord construction and internal parts as the Essence Reference-II cords.

ESP cords are UL approved

The premium materials endemic in the Essence-Reference II cords, made for extensive muscle strength needed to flex the cables around corners, rack posts, etc. In my audiophile rig, I have a four-glass shelf rack with three large column supports. The wall receptacle is behind the rear column. I really had to manhandle the ESP Essence Reference-II to get it to bend around the column. Like fighting an alligator!

Speaking of price, $2,000 for a power cord and $3,000 for the power strip ain’t pocket change. Of course, I know audiophiles who spend way more on their accessories than $2,000. And into the stratosphere for the components. These are the guys who will buy this cable. The demographic and the prices charged strike an equilibrium in this crazy world of audiophiles. If a product was priced too high, ESP would not be in business.

The verdict

Although the sonic benefits were subtle, my tests showed that the Essence Reference-II can improve sound quality by eliminating the potential resolution-robbing AC-line noise and maintaining optimum current for AC-intensive products, such as amplifiers.